Google already has a section of its search engine devoted to apps, although it’s very basic. Appgravity is a new service that has taken that idea of app search and is turning it into a service with a lot of potential.

Currently pulling all its data from the Android Market, Appgravity allows you to search for apps by name or by keywords. Results can be filtered by category and listed in order of relevance, age, rating and number of downloads. Once you’ve found the app you want, a button allows you to send a link to the Download or (for paid apps) Purchase page on the Market.

You could argue that you might as well search directly on the Android Market, but Appgravity offers a cleaner interface and different filtering tools. As it develops further, there will be further reasons to use the service. The Sunnyvale, California-based startup plans to add more app stores, starting with Amazon before expanding to cover small, independent sources. This will allow price comparison, letting you quickly discover the best place to buy a particular app. The team is also developing widgets and plugins for the likes of Blogger, WordPress, Eclipse and Netbeans.

When we tested the service, it found almost all of the apps we searched for, although one was missing. Appgravity’s Dustin Dickens explains that the way the service collects information from the Market is being improved to ensure it catches every app.

It certainly sounds like the team has had an uphill struggle to build a third-party service that works with the Android Market. “We, along with a few other companies and developers, have effectively reverse engineered the Android Market’s public API,” says Dickens. “There is a very tight-knit but open community hosted by Google centered around this ‘API’ which really exists more for Android and its close partners’ use, and not the third-party pseudo markets and search engines that have grown up around it. It has no official published publicly available documentation and is totally unsupported…a grey area in general.

“Google is cool with (Appgravity) – all roads still lead back to their Market and we sell AdSense ads, but they aren’t making it easy on us by publishing the API documentation or building nice clean web services for us,” Dickens adds.

Appgravity offers the potential for a different approach to app discovery services like Appsfire. The startup says that it’s preparing to close its first round of external funding, and it will be interesting to see how it develops in 2012.